How powerful would these DBZ characters be in DC?

Inspired by a recent thread about a what if Goku went into the DC Universe, comes this thread. Characters are often weakened or bolstered from previous incarnations of them due to plot. So if these DBZ characters were to be integrated (not just plopped into DC, but as if they were always there), how powerful would they be and their techniques at their max in comparison to DC characters?

1. Kid Buu

2. Super Janemba

3. Goku

4. Vegeta

5. Final Form Frieza

6. Perfect Cell

EDIT: 7. Legendary Super Saiyan Broly

Bonus: How would they be represented in the DC universe? For example, would Vegeta and Goku be survivors of Kryptonian as well? Would Frieza be similar to Darkseid and possibly an ally to him? Cell a creation from LexCorp with the abilities of most Justice League characters?

Just an interesting topic that has been lingering at the back of my head ever since I started lurking Comic Vine since early 2014. Just opened up this account no later than a month by now.

Bump. Now that I think about it, Perfect Cell is kind of like Imperiex. They both have the self-proclaimed goals of destroying the universe to make it 'pure' again.

They would make Goku a weakling by putting him at Superman level :(

Comparing DBZ to DC is the same as a battle, against the rules. Your bonus questions are acceptable, like the thread you were inspired by.